Date: Sat, 6 May 2000 12:50:04 -0600 (MDT) From: Nate Williams <nate@yogotech.com> To: Mike Smith <msmith@FreeBSD.ORG> Cc: nate@yogotech.com (Nate Williams), hackers@FreeBSD.ORG Subject: Re: [OT] Finding people with GSM phones (was Re: GPS heads up ) Message-ID: <200005061850.MAA18384@nomad.yogotech.com> In-Reply-To: <200005061855.LAA07340@mass.cdrom.com> References: <200005061840.MAA18274@nomad.yogotech.com> <200005061855.LAA07340@mass.cdrom.com>
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> > > With one tower, you're down to describing an arc along which > > > the phone is probably located; still pretty good when it comes to finding > > > someone. > > > > He seemed to imply that they could get it within 25m, even with one > > phone. Like I said, I don't understand how, but I didn't question his > > ability. Plus, he knows alot more about the stuff than I do. > > Well, assuming they have 100% antenna overlap (not unlikely) you could > just do phase comparisons between the antennae getting the squirt. If > these guys are as smart as you say (and I have no doubt at all about > that), 25m at near distance is probably not unrealistic. True. Up close, you can triangulate. > Ask him if they can still do it at 35km out (the outer limit for a normal > GSM cell). That'd really spook me. 8) He wasn't interested in talking about it when I started asking about single cell towers, so I never pressed him on the issue. Maybe he was afraid that the 100m accuracy claim would be found out to be un-doable, but the Feds claim 'it must be that accurate', and they aren't interested in spending the $$ for GPS receivers in the handhelds. Or, he's got it figured out, and is applying for a patent on it and didn't want to reveal his secrets. :) Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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